There are approximately 600 kinds of carotenoids naturally, but only six kinds of these have so far been produced industrially such as production by Roche Corporation and BASF Corporation. Lycopene as an important product has important functions on scavenging free radical, antiageing, inhibiting tumor, treating heart attack and so on (H. Gerster, J. Am. Coll. Nutr. 1997, 16, 109; Nutr. Cancer 1995, 24.257; E. Giovannucci. et al. J. Natl. Cancer Inst. 1995, 87, 1767; Chem. Abstracts 1990, 112 91375w), and is widely used for medicines, food additives, feed additives. Roche Corporation develops a synthesis route by the Witting Reaction, wherein it uses expensive and poisonous raw materials such as tri-phenyl phosphorous (K. Meyer, et al., Helv. Chim. Acta 1992, 75.1848). Other former synthesis methods use tri-phenyl phosphorous either (P. Karrer, et al., Helv. Chim. Acta 1950, 33, 1349; B. C. L. Weedon, et al., J. Chem. Soc. 1965, 2019; K. Bernhard and H. Mayer, Pure & Appl.-them. 1991, 63, 35).
It has been reported from Publication No. WO 0031086 (2000 Jun. 2) of PCT application that Babler J. H. et al. reported a new method of synthesizing lycopene by the Wittig-Horner Reaction, wherein 3,7,11-trimethyl-2,4,6,10-dodecatetraenyl phosphonic acid diethyl ester of formula (5) as a crucial intermediate proceeds a condensation reaction with decyl di-aldehyde by catalysis of bases for preparing lycopene, the whole synthesis sequence is described as follows.
Firstly, pseudoionone (2) reacts with ethynyl anion to produce tertiary alcohol (7) (3,7,11-trimethyl-4,6,10-dodecatrien-1-yn-3-ol):

Afterwards, tertiary alcohol (7) reacts with dialkyl chlorophosphite to produce propadiene pentadecyl phosphoric acid ester (6) (3,7,11-trimethyl-1,2,4,6,10-dodecapentaenyl phosphoric acid diethyl ester).

Secondly, propadiene pentadecyl phosphoric acid ester (6) is partially reduced and transformed to pentadecyl phosphoric acid ester (5) (3,7,11-trimethyl-2,4,6,10-dodecatetraenyl phosphoric acid diethyl ester):

Finally, pentadecyl phosphoric acid ester (5) proceeds a condensation reaction with decanal di-aldehyde (8) (2,7-dimenthyl-2,4,6-octatriene-1,8-dial) by catalysis of bases to obtain lycopene (1).

The method uses a new compound 2,4,6,10-pentadecatetraenyl phosphoric acid ester (5) as an intermediate to avoid uses of triphenyl phosphorous; and moreover uses pseudoionone as a raw material to obtain products of lycopene by reactions of four steps. The synthesis route thereof is concise, and has prominent improvement relative to former methods. However there are some problems in the method. Firstly it is difficulty for reactions of tertiary alcohol (7) with dialkyl chlorophosphite to produce propadiene pentadecyl phosphoric acid ester (6). Secondly it is hard to handle the reduction technology of propadiene pentadecyl phosphoric acid ester (6) selectively being reduced to pentadecyl phosphoric acid ester (5).
After studying features and preparation of 2,4,6,10-dodecatetraenyl phosphoric acid ester of formula (5), the inventors found that there would be a method of preparing products of structure analogue in early patents (U.S. Pat. No. 4,916,250). The process is by a condensation reaction of Wittig-Horner of C-14 aldehyde and methylene bisphosphonic acid tetraethyl ester to produce 1-enyl isomer thereof, and then to catalyze and rearrange by base to obtain 2-enyl isomer. As shown in the following reaction sequence.

The reaction sequence is concise, operable and high yield. Consequently it would be great advantages of preparing 2,4,6,10-pentadecatetraenyl phosphoric acid ester (5) by using C-14 aldehyde as raw materials and further produce lycopene.
PCT publication No. WO 0031086 and U.S. Pat. Nos. 4,916,250, 6,727,381, 4,000,131 and 5,061,819 are hereby incorporated by reference.
The inventors of the present invention prepare 2,4,6,10-pentadecatetraenyl phosphoric acid ester by using C-14 aldehyde as raw materials and further prepare lycopene according to methods of U.S. Pat. No. 4,916,250. As shown in the following reaction sequence.

The inventors of the present invention found a group of new compounds 1,4,6,10-pentadecatetraenyl phosphonic acid ester (4) in the synthesis process may be used as a crucial intermediate in the process. Mr. Shiqing Pi and Runbo Shen et al. mentioned in an early patent (U.S. Pat. No. 6,727,381) that a compound analogous to 1-enyl pentadecyl phosphonic acid ester directly reacts with C-5 aldehyde to produce Vitamin A. As shown in the following reaction sequence.

Accordingly, it would be reasonable to expect a new compound 1,4,6,10-pentadecatetraenyl phosphoric acid ester of formula (4), that is, 1,4,6,10-pentadecatetraenyl phosphoric acid ester of formula (4) directly proceeds a condensation reaction with decyl di-aldehyde of formula (8) to obtain lycopene of formula (1), but not by a rearrangement reaction from 1,4,6,10-pentadecatetraenyl phosphoric acid ester of formula (4) to 2,4,6,10-pentadecatetraenyl phosphoric acid ester of formula (5).